Clonogenic growth of human breast cancer cells co-cultured in direct contact with serum-activated fibroblasts

Prostate Cancer's Silent Partners: Fibroblasts and Their Influence on Glutamine Metabolism Manipulation

Cancer-associated fibroblast (CAF)s in the tumour microenvironment (TME) modulate the extracellular matrix, interact with cancer cells, and facilitate communication with infiltrating leukocytes, significantly contributing to cancer progression and therapeutic response. In prostate cancer (PCa), CAFs promote malignancy through metabolic rewiring, cancer stem cell regulation, and therapy resistance. Pre-clinical studies indicate that targeting amino acid metabolism, particularly glutamine (Gln) metabolism, reduces cancer proliferation and stemness. However, most studies lack the context of CAF-cancer interaction, focusing on monocultures. This study assesses the influence of CAFs on PCa growth by manipulating Gln metabolism using colour-labelled PCa cell lines (red) and fibroblast (green) in a co-culture system to evaluate CAFs' effects on PCa cell proliferation and clonogenic potential. CAFs increased the proliferation of hormone-sensitive LNCaP cells, whereas the castration-resistant C4-2 cells were unaffected. However, clonogenic growth increased in both cell lines. Gln deprivation and GLS1 inhibition experiments revealed that the increased growth rate of LNCAP cells was associated with increased dependence on Gln, which was confirmed by proteomic analyses. Tissue analysis of PCa patients revealed elevated GLS1 levels in both the PCa epithelium and stroma, suggesting that GLS1 is a therapeutic target. Moreover, the median overall survival analysis of GLS1 expression in the PCa epithelium and stroma identified a "high-risk" patient group that may benefit from GLS1-targeted therapies. Therefore, GLS1 targeting appears promising in castration-resistant PCa patients with high GLS1 epithelium and low GLS1 stromal expression.

Stromal Signals Dominate Gene Expression Signature Scores That Aim to Describe Cancer Cell-intrinsic Stemness or Mesenchymality Characteristics

Epithelial-to-mesenchymal transition (EMT) in cancer cells confers migratory abilities, a crucial aspect in the metastasis of tumors that frequently leads to death. In multiple studies, authors proposed gene expression signatures for EMT, stemness, or mesenchymality of tumors based on bulk tumor expression profiling. However, recent studies suggested that noncancerous cells from the microenvironment or macroenvironment heavily influence such signature profiles. Here, we strengthen these findings by investigating 11 published and frequently referenced gene expression signatures that were proposed to describe EMT-related (EMT, mesenchymal, or stemness) characteristics in various cancer types. By analyses of bulk, single-cell, and pseudobulk expression data, we show that the cell type composition of a tumor sample frequently dominates scores of these EMT-related signatures. A comprehensive, integrated analysis of bulk RNA sequencing (RNA-seq) and single-cell RNA-seq data shows that stromal cells, most often fibroblasts, are the main drivers of EMT-related signature scores. We call attention to the risk of false conclusions about tumor properties when interpreting EMT-related signatures, especially in a clinical setting: high patient scores of EMT-related signatures or calls of "stemness subtypes" often result from low cancer cell content in tumor biopsies rather than cancer cell-specific stemness or mesenchymal/EMT characteristics.

SIGNIFICANCE

Cancer self-renewal and migratory abilities are often characterized via gene module expression profiles, also called EMT or stemness gene expression signatures. Using published clinical tumor samples, cancer cell lines, and single cancer cells, we highlight the dominating influence of noncancer cells in low cancer cell content biopsies on their scores. We caution on their application for low cancer cell content clinical cancer samples with the intent to assign such characteristics or subtypes.

Using picoliter droplet deposition to track clonal competition in adherent and organoid cancer cell cultures

Clonal growth and competition underlie processes of key relevance in etiology, progression and therapy response across all cancers. Here, we demonstrate a novel experimental approach, based on multi-color, fluorescent tagging of cell nuclei, in combination with picoliter droplet deposition, to study the clonal dynamics in two- and three-dimensional cell cultures. The method allows for the simultaneous visualization and analysis of multiple clones in individual multi-clonal colonies, providing a powerful tool for studying clonal dynamics and identifying clonal populations with distinct characteristics. Results of our experiments validate the utility of the method in studying clonal dynamics in vitro, and reveal differences in key aspects of clonal behavior of different cancer cell lines in monoculture conditions, as well as in co-cultures with stromal fibroblasts.

Fibronectin fragments generated by pancreatic trypsin act as endogenous inhibitors of pancreatic tumor growth

BACKGROUND

The pancreatic microenvironment has a defensive role against cancer but it can acquire tumor-promoting properties triggered by multiple mechanisms including alterations in the equilibrium between proteases and their inhibitors. The identification of proteolytic events, targets and pathways would set the basis for the design of new therapeutic approaches.

METHODS AND RESULTS

Here we demonstrate that spheroids isolated from human and murine healthy pancreas and co-transplanted orthotopically with pancreatic ductal adenocarcinoma (PDAC) in mouse pancreas inhibited tumor growth. The effect was mediated by trypsin-generated fibronectin (FN) fragments released by pancreatic spheroids. Tumor inhibition was observed also in a model of acute pancreatitis associated with trypsin activation. Mass spectrometry proteomic analysis of fragments and mAb against different FN epitopes identified the FN type III domain as responsible for the activity. By inhibiting integrin α5β1, FAK and FGFR1 signaling, the fragments induced tumor cell detachment and reduced cell proliferation. Consistent with the mutual relationship between the two pathways, FGF2 restored both FGFR1 and FAK signaling and promoted PDAC cell adhesion and proliferation. FAK and FGFR inhibitors additively inhibited PDAC growth in vitro and in orthotopic in vivo models.

CONCLUSIONS

This study identifies a novel role for pancreatic trypsin and fibronectin cleavage as a mechanism of protection against cancer by the pancreatic microenvironment. The finding of a FAK-FGFR cross-talk in PDAC support the combination of FAK and FGFR inhibitors for PDAC treatment to emulate the protective effect of the normal pancreas against cancer.

Three-Dimensional Breast Cancer Model to Investigate CCL5/CCR1 Expression Mediated by Direct Contact between Breast Cancer Cells and Adipose-Derived Stromal Cells or Adipocytes

The tumor microenvironment (TME) in breast cancer is determined by the complex crosstalk of cancer cells with adipose tissue-inherent cells such as adipose-derived stromal cells (ASCs) and adipocytes resulting from the local invasion of tumor cells in the mammary fat pad. This leads to heterotypic cellular contacts between these cell types. To adequately mimic the specific cell-to-cell interaction in an in vivo-like 3D environment, we developed a direct co-culture spheroid model using ASCs or differentiated adipocytes in combination with MDA-MB-231 or MCF-7 breast carcinoma cells. Co-spheroids were generated in a well-defined and reproducible manner in a high-throughput process. We compared the expression of the tumor-promoting chemokine CCL5 and its cognate receptors in these co-spheroids to indirect and direct standard 2D co-cultures. A marked up-regulation of CCL5 and in particular the receptor CCR1 with strict dependence on cell-cell contacts and culture dimensionality was evident. Furthermore, the impact of direct contacts between ASCs and tumor cells and the involvement of CCR1 in promoting tumor cell migration were demonstrated. Overall, these results show the importance of direct 3D co-culture models to better represent the complex tumor-stroma interaction in a tissue-like context. The unveiling of tumor-specific markers that are up-regulated upon direct cell-cell contact with neighboring stromal cells, as demonstrated in the 3D co-culture spheroids, may represent a promising strategy to find new targets for the diagnosis and treatment of invasive breast cancer.

Mast cell-T cell axis alters development of colitis-dependent and colitis-independent colorectal tumours: potential for therapeutically targeting via mast cell inhibition

Background

Colorectal cancer (CRC) has a high mortality rate and can develop in either colitis-dependent (colitis-associated (CA)-CRC) or colitis-independent (sporadic (s)CRC) manner. There has been a significant debate about whether mast cells (MCs) promote or inhibit the development of CRC. Herein we investigated MC activity throughout the multistepped development of CRC in both human patients and animal models.

Methods

We analyzed human patient matched samples of healthy colon vs CRC tissue alongside conducting a The Cancer Genome Atlas-based immunogenomic analysis and multiple experiments employing genetically engineered mouse (GEM) models.

Results

Analyzing human CRC samples revealed that MCs can be active or inactive in this disease. An activated MC population decreased the number of tumor-residing CD8 T cells. In mice, MC deficiency decreased the development of CA-CRC lesions, while it increased the density of tumor-based CD8 infiltration. Furthermore, co-culture experiments revealed that tumor-primed MCs promote apoptosis in CRC cells. In MC-deficient mice, we found that MCs inhibited the development of sCRC lesions. Further exploration of this with several GEM models confirmed that different immune responses alter and are altered by MC activity, which directly alters colon tumorigenesis. Since rescuing MC activity with bone marrow transplantation in MC-deficient mice or pharmacologically inhibiting MC effects impacts the development of sCRC lesions, we explored its therapeutic potential against CRC. MC activity promoted CRC cell engraftment by inhibiting CD8+ cell infiltration in tumors, pharmacologically blocking it inhibits the ability of allograft tumors to develop. This therapeutic strategy potentiated the cytotoxic activity of fluorouracil chemotherapy.

Conclusion

Therefore, we suggest that MCs have a dual role throughout CRC development and are potential druggable targets against this disease.

Meaningful connections: Interrogating the role of physical fibroblast cell-cell communication in cancer

As part of the connective tissue, activated fibroblasts play an important role in development and disease pathogenesis, while quiescent resident fibroblasts are responsible for sustaining tissue homeostasis. Fibroblastic activation is particularly evident in the tumor microenvironment where fibroblasts transition into tumor-supporting cancer-associated fibroblasts (CAFs), with some CAFs maintaining tumor-suppressive functions. While the tumor-supporting features of CAFs and their fibroblast-like precursors predominantly function through paracrine chemical communication (e.g., secretion of cytokine, chemokine, and more), the direct cell-cell communication that occurs between fibroblasts and other cells, and the effect that the remodeled CAF-generated interstitial extracellular matrix has in these types of cellular communications, remain poorly understood. Here, we explore the reported roles fibroblastic cell-cell communication play within the cancer stroma context and highlight insights we can gain from other disciplines.

Intercellular interactions between mast cells and stromal fibroblasts obtained from canine cutaneous mast cell tumours

Mast cell tumours (MCTs) are the most frequent malignant skin neoplasm in dogs. Due to the difficulty in purifying large numbers of canine neoplastic mast cells, relatively little is known about their properties. A reproducible in vitro model is needed to increase the understanding about the phenotype and functional properties of neoplastic mast cells. In the present study, we describe the establishment of primary cocultures of neoplastic mast cells from canine cutaneous MCTs and cancer-associated fibroblasts. We confirmed the inability of canine neoplastic mast cells to remain viable for long periods in vitro without the addition of growth factors or in vivo passages in mice. Using a transwell system, we observed that mast cell viability was significantly higher when there is cell-to-cell contact in comparison to non-physical contact conditions and that mast cell viability was significantly higher in high-grade than in low-grade derived primary cultures. Moreover, the use of conditioned medium from co-cultured cells led to a significantly higher tumoral mast cell viability when in monoculture. Signalling mechanisms involved in these interactions might be attractive therapeutic targets to block canine MCT progression and deserve more in-depth investigations.

A CD10-OGP Membrane Peptolytic Signaling Axis in Fibroblasts Regulates Lipid Metabolism of Cancer Stem Cells via SCD1

Carcinoma-associated fibroblasts (CAFs) consist of heterogeneous subpopulations that play a critical role in the dynamics of the tumor microenvironment. The extracellular signals of CAFs have been attributed to the extracellular matrix, cytokines, cell surface checkpoints, and exosomes. In the present study, it is demonstrated that the CD10 transmembrane hydrolase expressed on a subset of CAFs supports tumor stemness and induces chemoresistance. Mechanistically, CD10 degenerates an antitumoral peptide termed osteogenic growth peptide (OGP). OGP restrains the expression of rate-limiting desaturase SCD1 and inhibits lipid desaturation, which is required for cancer stem cells (CSCs). Targeting CD10 significantly improves the efficacy of chemotherapy in vivo. Clinically, CD10-OGP signals are associated with the response to neoadjuvant chemotherapy in patients with breast cancer. The collective data suggest that a nexus between the niche and lipid metabolism in CSCs is a promising therapeutic target for breast cancer.

Using dynamic cell communication improves treatment strategies of breast cancer

Several insights from the clinical treatment of breast cancer patients have revealed that only a portion of patients achieve the expected curative effect after traditional targeted therapy, that surgical treatment may promote the development of cancer metastasis, and that the optimal combination of neoadjuvant chemotherapy and traditional treatment is not clear. Therefore, a more precise classification of breast cancer and selection of treatment methods should be undertaken to improve the efficacy of clinical treatment. In the clinical treatment of breast cancer, cell communication molecules are often selected as therapeutic targets. However, various cell communications are not static. Their dynamic changes are related to communicating cells, communicating molecules, and various intertwined internal and external environmental factors. Understanding the dynamic microenvironment can help us improve therapeutic efficacy and provide new ways to more accurately determine the cancer status. Therefore, this review describes multiple types of cellular communication in the breast cancer microenvironment and incorporates internal and external environmental factors as variable signaling factors in cell communication. Using dynamic and developmental concepts, we summarize the functional changes in signaling molecules and cells to aid in the diagnosis and treatment of breast cancer.

Aberrant Expression of Syndecan-1 in Cervical Cancers

Syndecan-1, is a transmembrane heparan/chondroitin sulfate proteoglycan necessary for cell-cell and cell-matrix interactions. Its decreased level on the cell surface correlates with poor prognosis in several tumor types. Aberrant stromal localization of syndecan-1 is also considered an unfavorable prognostic factor in various human malignancies. In the presented work the question was addressed if changes in syndecan-1 expression are related to the prognosis of cervical cancer. Immunohistochemistry for syndecan-1 extracellular domain was performed on surgical specimens of primary cervical cancer. To follow the communication between tumor cells and stromal fibroblasts, their mono-and co-cultures were studied, detecting the expression of syndecan-1, smooth muscle actin, vimentin, and desmin. Immunohistochemistry of tumorous specimens revealed that while cell surface syndecan-1 expression was reduced on cancer cells, it appeared on the surface of tumor-associated fibroblasts. Until year 7, the cohort with high cell surface syndecan-1 expression had significantly longer survival. No difference in the same time-period could be detected when stromal syndecan-1 expression was analyzed. In vitro analysis revealed, that tumor cells can induce syndecan-1 expression on fibroblast, and fibroblasts showed that fibroblast-like cells are built by two cell types: (a) syndecan-1 positive, cytokeratin negative real fibroblasts, and (b) syndecan-1 and cytokeratin positive epithelial-mesenchymal transformed tumor cells. Syndecan-1 on the surface of cancer cells appears to be a positive prognostic marker. Although syndecan-1 positive fibroblasts promote tumor cell proliferation in vitro, we failed to detect their cancer promoting effect in vivo.

Novel Assay Analyzing Tropism between Adipose-Derived Stem Cells and Breast Cancer Cells Reveals a Low Oncogenic Response

Introduction

In the surgical world of breast cancer reconstruction, fat grafting is commonly viewed as an oncogenic risk. Scientific studies add confusion, given the stark lack of clinical evidence suggesting pro-oncogenic links. Typically, classic migration assays (e.g., Boyden chamber) between adipose-derived stem cells and breast cancer cells define this cell relationship as pro-oncogenic.

Objective

We sought to develop a new migration model which better explains existing clinical data.

Methods

Silicon chambers were used to seed isolated populations of cells simultaneously in culture dish. Once cells had adhered, chambers were removed and cells were allowed to follow natural trophic cues. Multiple permutations of MDA-MB-231, MCF-7, HS-27, and ASCs were engineered. Cells were stained with MitoTracker for fluorescent visualization. A human cytokine array (RayBiotech) was performed on the media of migrating assays. Cellular tropism and blot intensity were quantitatively measured in Image J.

Results

An in vitro model was successfully constructed where ASCs reproducibly and freely migrated. Cytokine arrays reveal higher levels of IL-6 and CCL2 in the media of Boyden chambers containing ASCs and MDA-MB-231, compared to the novel assay, comprised of the same cell numbers, types, and incubation times.

Conclusion

These data collectively show for the first time the attraction of ASCs to malignant breast cancer cells; a phenomenon which many ASC studies infer. The cytokine profile of the novel system described is less oncogenic than the commonly described Boyden chamber. These data integrate better into the clinical data, which fail to link cancer recurrence with fat grafting.

The tip link protein Cadherin-23: From Hearing Loss to Cancer

Cadherin-23 is an atypical member of the cadherin superfamily, with a distinctly long extracellular domain. It has been known to be a part of the tip links of the inner ear mechanosensory hair cells. Several studies have been carried out to understand the role of Cadherin-23 in the hearing mechanism and defects in the CDH23 have been associated with hearing impairment resulting from defective or absence of tip links. Recent studies have highlighted the role of Cadherin-23 in several pathological conditions, including cancer, suggesting the presence of several unknown functions. Initially, it was proposed that Cadherin-23 represents a yet unspecified subtype of Cadherins; however, no other proteins with similar characteristics have been identified, till date. It has a unique cytoplasmic domain that does not bear a β-catenin binding region, but has been demonstrated to mediate cell-cell adhesions. Several protein interacting partners have been identified for Cadherin-23 and the roles of their interactions in various cellular mechanisms are yet to be explored. This review summarizes the characteristics of Cadherin-23 and its roles in several pathologies including cancer.

Nanomelatonin triggers superior anticancer functionality in a human malignant glioblastoma cell line

Melatonin (MEL) has promising medicinal value as an anticancer agent in a variety of malignancies, but there are difficulties in achieving a therapeutic dose due to its short half-life, low bioavailability, poor solubility and extensive first-pass metabolism. In this study chitosan/tripolyphosphate (TPP) nanoparticles were prepared by an ionic gelation method to overcome the therapeutic challenges of melatonin and to improve its anticancer efficacy. Characterization of the melatonin-loaded chitosan (MEL-CS) nanoformulation was performed using transmission and scanning electron microscopies, dynamic light scattering, Fourier transform infrared spectroscopy, Raman spectroscopy and x-ray diffraction. In vitro release, cellular uptake and efficacy studies were tested for their enhanced anticancer potential in human U87MG glioblastoma cells. Confocal studies revealed higher cellular uptake of MEL-CS nanoparticles and enhanced anticancer efficacy in human malignant glioblastoma cancer cells than in healthy non-malignant human HEK293T cells in mono- and co-culture models. Our study has shown for the first time that MEL-CS nanocomposites are therapeutically more effective as compared to free MEL at inducing functional anticancer efficacy in the human brain tumour U87MG cell line.

Characterization of human breast cancer tissues by infrared imaging

Fourier Transform InfraRed (FTIR) spectroscopy coupled to microscopy (IR imaging) has shown unique advantages in detecting morphological and molecular pathologic alterations in biological tissues. The aim of this study was to evaluate the potential of IR imaging as a diagnostic tool to identify characteristics of breast epithelial cells and the stroma. In this study a total of 19 breast tissue samples were obtained from 13 patients. For 6 of the patients, we also obtained Non-Adjacent Non-Tumor tissue samples. Infrared images were recorded on the main cell/tissue types identified in all breast tissue samples. Unsupervised Principal Component Analyses and supervised Partial Least Square Discriminant Analyses (PLS-DA) were used to discriminate spectra. Leave-one-out cross-validation was used to evaluate the performance of PLS-DA models. Our results show that IR imaging coupled with PLS-DA can efficiently identify the main cell types present in FFPE breast tissue sections, i.e. epithelial cells, lymphocytes, connective tissue, vascular tissue and erythrocytes. A second PLS-DA model could distinguish normal and tumor breast epithelial cells in the breast tissue sections. A patient-specific model reached particularly high sensitivity, specificity and MCC rates. Finally, we showed that the stroma located close or at distance from the tumor exhibits distinct spectral characteristics. In conclusion FTIR imaging combined with computational algorithms could be an accurate, rapid and objective tool to identify/quantify breast epithelial cells and differentiate tumor from normal breast tissue as well as normal from tumor-associated stroma, paving the way to the establishment of a potential complementary tool to ensure safe tumor margins.

Biosensing breast cancer cells based on a three-dimensional TIO2 nanomembrane transducer

The early diagnosis of breast cancer is crucial for the successful treatment and recovery phases of the patients suffering from the disease. Although mammography is considered the gold standard for diagnosis, it fails to detect some cancers in high-density breasts. In this work, we propose for the first time a tridimensional biosensor platform, to be used on an electrochemical point-of-care device. The bioconjugated platform is constructed on a series of covalent linkages between lectin molecules and a cysteine layer immobilized over gold-coated TiO₂ butterfly-like tridimensional nanomembranes. Through the use of vegetal lectins, we managed to take advantage of the markedly atypical glycomic profile of the cancerous mammalian cell membrane and successfully made a distinction between highly invasive (T47D) and less invasive (MCF7) cancer cell lines. The selectivity of the biosensor was tested by using normal human skin-fibroblast. The proposed cytosensor demonstrated limits of detection as low as 10 cells mL^-1 for every cell line and a linear range from 10 to 1.0×10⁶ cells mL^-1. Considering that electrochemical impedance values can be correlated with the number of breast cancer cells present in the sample, we suggest that the proposed platform could be useful in facilitating the diagnosis of cancer.

Serum uPAR as Biomarker in Breast Cancer Recurrence: A Mathematical Model

There are currently over 2.5 million breast cancer survivors in the United States and, according to the American Cancer Society, 10 to 20 percent of these women will develop recurrent breast cancer. Early detection of recurrence can avoid unnecessary radical treatment. However, self-examination or mammography screening may not discover a recurring cancer if the number of surviving cancer cells is small, while biopsy is too invasive and cannot be frequently repeated. It is therefore important to identify non-invasive biomarkers that can detect early recurrence. The present paper develops a mathematical model of cancer recurrence. The model, based on a system of partial differential equations, focuses on tissue biomarkers that include the plasminogen system. Among them, only uPAR is known to have significant correlation to its concentration in serum and could therefore be a good candidate for serum biomarker. The model includes uPAR and other associated cytokines and cells. It is assumed that the residual cancer cells that survived primary cancer therapy are concentrated in the same location within a region with a very small diameter. Model simulations establish a quantitative relation between the diameter of the growing cancer and the total uPAR mass in the cancer. This relation is used to identify uPAR as a potential serum biomarker for breast cancer recurrence.

Fibroblasts Influence Survival and Therapeutic Response in a 3D Co-Culture Model

In recent years, evidence has indicated that the tumor microenvironment (TME) plays a significant role in tumor progression. Fibroblasts represent an abundant cell population in the TME and produce several growth factors and cytokines. Fibroblasts generate a suitable niche for tumor cell survival and metastasis under the influence of interactions between fibroblasts and tumor cells. Investigating these interactions requires suitable experimental systems to understand the cross-talk involved. Most in vitro experimental systems use 2D cell culture and trans-well assays to study these interactions even though these paradigms poorly represent the tumor, in which direct cell-cell contacts in 3D spaces naturally occur. Investigating these interactions in vivo is of limited value due to problems regarding the challenges caused by the species-specificity of many molecules. Thus, it is essential to use in vitro models in which human fibroblasts are co-cultured with tumor cells to understand their interactions. Here, we developed a 3D co-culture model that enables direct cell-cell contacts between pancreatic, breast and or lung tumor cells and human fibroblasts/ or tumor-associated fibroblasts (TAFs). We found that co-culturing with fibroblasts/TAFs increases the proliferation in of several types of cancer cells. We also observed that co-culture induces differential expression of soluble factors in a cancer type-specific manner. Treatment with blocking antibodies against selected factors or their receptors resulted in the inhibition of cancer cell proliferation in the co-cultures. Using our co-culture model, we further revealed that TAFs can influence the response to therapeutic agents in vitro. We suggest that this model can be reliably used as a tool to investigate the interactions between a tumor and the TME.

The role of the cell-cell interactions in cancer progression

In the field of cancer research, scientific investigations are based on analysing differences in the secretome, the proteome, the transcriptome, the expression of cell surface molecules, and the deregulation of signal transduction pathways between neoplastic and normal cells. Accumulating evidence indicates a crucial role in carcinogenesis concerning not only stromal cells but also normal cells from target organs and tissue where tumours emerge. The tumour microenvironment (TME) definitively plays an important role in regulating neighbouring cell behaviour. To date, limited attention has been focused upon interactions between cancer cells and normal cells. This review concentrates on the interactions between stromal and healthy cells from the TME in cancer development. In the article, the authors also describe mutations, genes and proteins expression pattern that are involved in tumour development in target organ.

TGF-beta receptor type-2 expression in cancer-associated fibroblasts regulates breast cancer cell growth and survival and is a prognostic marker in pre-menopausal breast cancer

Transforming growth factor-beta (TGF-β) is a pleiotropic cytokine with the capability to act as tumour suppressor or tumour promoter depending on the cellular context. TGF-beta receptor type-2 (TGFBR2) is the ligand-binding receptor for all members of the TGF-β family. Data from mouse model experiments demonstrated that loss of Tgfbr2 expression in mammary fibroblasts was linked to tumour initiation and metastasis. Using a randomised tamoxifen trial cohort including in total 564 invasive breast carcinomas, we examined TGFBR2 expression (n=252) and phosphorylation level of downstream target SMAD2 (pSMAD2) (n=319) in cancer-associated fibroblasts (CAFs) and assessed links to clinicopathological markers, prognostic and treatment-predictive values. The study revealed that CAF-specific TGFBR2 expression correlated with improved recurrence-free survival. Multivariate analysis confirmed CAF-TGFBR2 to be an independent prognostic marker (multivariate Cox regression, hazard ratio: 0.534, 95% (CI): 0.360-0.793, P=0.002). CAF-specific pSMAD2 levels, however, did not associate with survival outcome. Experimentally, TGF-β signalling in fibroblasts was modulated using a TGF-β ligand and inhibitor or through lentiviral short hairpin RNA-mediated TGFBR2-specific knockdown. To determine the role of fibroblastic TGF-β pathway on breast cancer cells, we used cell contact-dependent cell growth and clonogenicity assays, which showed that knockdown of TGFBR2 in CAFs resulted in increased cell growth, proliferation and clonogenic survival. Further, in a mouse model transfected CAFs were co-injected with MCF7 and tumour weight and proportion was monitored. We found that mouse xenograft tumours comprising TGFBR2 knockdown fibroblasts were slightly bigger and displayed increased tumour cell capacity. Overall, our data demonstrate that fibroblast-related biomarkers possess clinically relevant information and that fibroblasts confer effects on breast cancer cell growth and survival. Regulation of tumour-stromal cross-talk through fibroblastic TGF-β pathway may depend on fibroblast phenotype, emphasising the importance to characterise tumour microenvironment subtypes.

Regulation of tumor dormancy and role of microenvironment: a mathematical model

Herein, a mathematical model of a molecular control system for the regulation of secondary tumors is formulated and analyzed to explore how secondary tumors can be controlled by a primary tumor with/without a surgery and the microenvironment. This control system is composed of fibroblast growth factor-2 (FGF2), urokinase-type plasminogen activator (uPA), plasmin, transforming growth factor-beta (TGFβ), latent TGFβ (LTGFβ), and tumor density. The control of secondary tumors by primary tumors was first modeled by Boushaba, Nilsen-Hamiton and Levine in [46]. The model is based on the idea that the vascularization of a secondary tumor can be suppressed by inhibitors from a larger primary tumor. The emergence of tumors at secondary sites 5-7 cm from a primary site was observed after surgical removal of the primary tumor in silico. The model supports the notion that the fate of secondary tumors after surgery depends on the distance from the primary tumor and the surrounding microenvironment. As such, the primary tumor did not influence the growth of remote secondary tumors, but it could effectively suppress the growth of the secondary tumors if they were too close to the primary tumor, even after it was removed. Thus, the model predicts the emergence of secondary tumors after the excision of the primary tumor when the distance between these tumors is in the "distance window." It also predicts that the growth behaviors of the secondary tumors depend on the local microenvironment. Based on these findings, we propose several treatment options for better clinical outcomes.

A hybrid model of tumor-stromal interactions in breast cancer

Ductal carcinoma in situ (DCIS) is an early stage noninvasive breast cancer that originates in the epithelial lining of the milk ducts, but it can evolve into comedo DCIS and ultimately, into the most common type of breast cancer, invasive ductal carcinoma. Understanding the progression and how to effectively intervene in it presents a major scientific challenge. The extracellular matrix (ECM) surrounding a duct contains several types of cells and several types of growth factors that are known to individually affect tumor growth, but at present the complex biochemical and mechanical interactions of these stromal cells and growth factors with tumor cells is poorly understood. Here we develop a mathematical model that incorporates the cross-talk between stromal and tumor cells, which can predict how perturbations of the local biochemical and mechanical state influence tumor evolution. We focus on the EGF and TGF-β signaling pathways and show how up- or down-regulation of components in these pathways affects cell growth and proliferation. We then study a hybrid model for the interaction of cells with the tumor microenvironment (TME), in which epithelial cells (ECs) are modeled individually while the ECM is treated as a continuum, and show how these interactions affect the early development of tumors. Finally, we incorporate breakdown of the epithelium into the model and predict the early stages of tumor invasion into the stroma. Our results shed light on the interactions between growth factors, mechanical properties of the ECM, and feedback signaling loops between stromal and tumor cells, and suggest how epigenetic changes in transformed cells affect tumor progression.

The gene expression profiles of canine mammary cancer cells grown with carcinoma-associated fibroblasts (CAFs) as a co-culture in vitro

Background

It is supposed that fibroblasts present in tumour microenvironment increase cancer invasiveness and its ability to metastasize but the mechanisms have not been clearly defined yet. Thus, the current study was designed to assess changes in gene expression in five various cancer cell lines grown as a co-culture with the carcinoma-associated fibroblasts (CAFs) in vitro.

Results

A carcinoma-associated fibroblast cell line was isolated from a canine mammary cancer. Then, a co-culture of cancer cells with the CAFs was established and maintained for 72 hrs. Having sorted the cells, a global gene expression in cancer cells using DNA microarrays was examined. The analysis revealed an up-regulation of 100 genes and a down-regulation of 106 genes in the cancer cells grown as a co-culture with the CAFs in comparison to control conditions. The PANTHER binomial statistics tool was applied to determine statistically over-manifested pathways (p < 0.05). Bulk of the up-regulated genes are involved in the adhesion, the angiogenesis, the epithelial-mesenchymal transition (EMT) and generally take part in the developmental processes. These results were further confirmed using real-time qPCR. Moreover, a wound-healing assay and growth characteristics on Matrigel matrix showed that CAFs increase cancer cell migration and matrix invasion.

Conclusion

The results of the current study showed that the co-culturing of cancer cells and the CAFs caused significant changes to the cancer gene expression. The presence of the CAFs in a microenvironment of cancer cells promotes adhesion, angiogenesis and EMT.

Morphometric characteristics of basal cell carcinoma peritumoral stroma varies among basal cell carcinoma subtypes

BACKGROUND

The role that the peritumoral stroma plays in the growth of tumours is currently poorly understood. In this manuscript the morphometric characteristics of basal cell carcinoma subtypes and their associated peritumoral stromas are presented.

METHODS

Ninety eight digitized basal cell carcinoma histology slides were categorized as infiltrative, nodular, or superficial subtypes, and were analysed using a combination of manual and computer-assisted approaches. The morphometric characteristics of the tumour nests and their associated peritumoral stroma were quantified, and the presence of a marked immune reaction or elastosis was noted.

RESULTS

The tumour to stroma ratio was different among each tumour subtype. Elastosis was identified in a greater proportion of the infiltrative tumours.

CONCLUSIONS

Quantitative differences exist between the peritumoral stroma of basal cell carcinoma subtypes. Future work exploring the relation between these morphometric differences and biochemical variations in peritumoral stroma may further our understanding of the biology of carcinoma development.

TRIAL REGISTRATION

Not applicable.

Cadherin-23 mediates heterotypic cell-cell adhesion between breast cancer epithelial cells and fibroblasts

In the early stages of breast cancer metastasis, epithelial cells penetrate the basement membrane and invade the surrounding stroma, where they encounter fibroblasts. Paracrine signaling between fibroblasts and epithelial tumor cells contributes to the metastatic cascade, but little is known about the role of adhesive contacts between these two cell types in metastasis. Here we show that MCF-7 breast cancer epithelial cells and normal breast fibroblasts form heterotypic adhesions when grown together in co-culture, as evidenced by adhesion assays. PCR and immunoblotting show that both cell types express multiple members of the cadherin superfamily, including the atypical cadherin, cadherin-23, when grown in isolation and in co-culture. Immunocytochemistry experiments show that cadherin-23 localizes to homotypic adhesions between MCF-7 cells and also to heterotypic adhesions between the epithelial cells and fibroblasts, and antibody inhibition and RNAi experiments show that cadherin-23 plays a role in mediating these adhesive interactions. Finally, we show that cadherin-23 is upregulated in breast cancer tissue samples, and we hypothesize that heterotypic adhesions mediated by this atypical cadherin may play a role in the early stages of metastasis.

A versatile valve-enabled microfluidic cell co-culture platform and demonstration of its applications to neurobiology and cancer biology

A versatile microfluidic platform allowing co-culture of multiple cell populations in close proximity with separate control of their microenvironments would be extremely valuable for many biological applications. Here, we report a simple and compact microfluidic platform that has these desirable features and allows for real-time, live-cell imaging of cell-cell interactions. Using a pneumatically/hydraulically controlled poly(dimethylsiloxane) (PDMS) valve barrier, distinct cell types can be cultured in side-by-side microfluidic chambers with their optimum culture media and treated separately without affecting the other cell population. The platform is capable of both two-dimensional and three-dimensional cell co-culture and through variations of the valve barrier design, the platform allows for cell-cell interactions through either direct cell contact or soluble factors alone. The platform has been used to perform dynamic imaging of synapse formation in hippocampal neurons by separate transfection of two groups of neurons with fluorescent pre- and post-synaptic protein markers. In addition, cross-migration of 4T1 tumor cells and endothelial cells has been studied under normoxic and hypoxic conditions, which revealed different migration patterns, suggesting the importance of the microenvironments in cell-cell interactions and biological activities.

The role of the microenvironment in tumor growth and invasion

Mathematical modeling and computational analysis are essential for understanding the dynamics of the complex gene networks that control normal development and homeostasis, and can help to understand how circumvention of that control leads to abnormal outcomes such as cancer. Our objectives here are to discuss the different mechanisms by which the local biochemical and mechanical microenvironment, which is comprised of various signaling molecules, cell types and the extracellular matrix (ECM), affects the progression of potentially-cancerous cells, and to present new results on two aspects of these effects. We first deal with the major processes involved in the progression from a normal cell to a cancerous cell at a level accessible to a general scientific readership, and we then outline a number of mathematical and computational issues that arise in cancer modeling. In Section 2 we present results from a model that deals with the effects of the mechanical properties of the environment on tumor growth, and in Section 3 we report results from a model of the signaling pathways and the tumor microenvironment (TME), and how their interactions affect the development of breast cancer. The results emphasize anew the complexities of the interactions within the TME and their effect on tumor growth, and show that tumor progression is not solely determined by the presence of a clone of mutated immortal cells, but rather that it can be 'community-controlled'.

Tumor cells proliferation and migration under the influence of their microenvironment

It is well known that tumor microenvironment affects tumor growth and metastasis: Tumor cells may proliferate at different rates and migrate in different patterns depending on the microenvironment in which they are embedded. There is a huge literature that deals with mathematical models of tumor growth and proliferation, in both the avascular and vascular phases. In particular, a review of the literature of avascular tumor growth (up to 2006) can be found in Lolas (G. Lolas, Lecture Notes in Mathematics, Springer Berlin / Heidelberg, 1872, 77 (2006)). In this article we report on some of our recent work. We consider two aspects, proliferation and of migration, and describe mathematical models based on in vitro experiments. Simulations of the models are in agreement with experimental results. The models can be used to generate hypotheses regarding the development of drugs which will confine tumor growth.

UMARS: Un-MAppable Reads Solution

Background

Un-MAppable Reads Solution (UMARS) is a user-friendly web service focusing on retrieving valuable information from sequence reads that cannot be mapped back to reference genomes. Recently, next-generation sequencing (NGS) technology has emerged as a powerful tool for generating high-throughput sequencing data and has been applied to many kinds of biological research. In a typical analysis, adaptor-trimmed NGS reads were first mapped back to reference sequences, including genomes or transcripts. However, a fraction of NGS reads failed to be mapped back to the reference sequences. Such un-mappable reads are usually imputed to sequencing errors and discarded without further consideration.

Methods

We are investigating possible biological relevance and possible sources of un-mappable reads. Therefore, we developed UMARS to scan for virus genomic fragments or exon-exon junctions of novel alternative splicing isoforms from un-mappable reads. For mapping un-mappable reads, we first collected viral genomes and sequences of exon-exon junctions. Then, we constructed UMARS pipeline as an automatic alignment interface.

Results

By demonstrating the results of two UMARS alignment cases, we show the applicability of UMARS. We first showed that the expected EBV genomic fragments can be detected by UMARS. Second, we also detected exon-exon junctions from un-mappable reads. Further experimental validation also ensured the authenticity of the UMARS pipeline. The UMARS service is freely available to the academic community and can be accessed via http://musk.ibms.sinica.edu.tw/UMARS/.

Conclusions

In this study, we have shown that some un-mappable reads are not caused by sequencing errors. They can originate from viral infection or transcript splicing. Our UMARS pipeline provides another way to examine and recycle the un-mappable reads that are commonly discarded as garbage.

Benign mammary epithelial cells enhance the transformed phenotype of human breast cancer cells

Background

Recent research has yielded a wealth of data underscoring the key role of the cancer microenvironment, especially immune and stromal cells, in the progression of cancer and the development of metastases. However, the role of adjacent benign epithelial cells, which provide initial cell-cell contacts with cancer cells, in tumor progression has not been thoroughly examined. In this report we addressed the question whether benign MECs alter the transformed phenotype of human breast cancer cells.

Methods

We used both in vitro and in vivo co-cultivation approaches, whereby we mixed GFP-tagged MCF-10A cells (G2B-10A), as a model of benign mammary epithelial cells (MECs), and RFP-tagged MDA-MB-231-TIAS cells (R2-T1AS), as a model of breast cancer cells.

Results

The in vitro studies showed that G2B-10A cells increase the colony formation of R2-T1AS cells in both soft agar and clonogenicity assays. Conditioned media derived from G2B-10A cells enhanced colony formation of R2-T1AS cells, whereas prior paraformaldehyde (PFA) fixation of G2B-10A cells abrogated this enhancement effect. Moreover, two other models of benign MECs, MCF-12A and HuMECs, also enhanced R2-T1AS colony growth in soft agar and clonogenicity assays. These data reveal that factors secreted by benign MECs are responsible for the observed enhancement of the R2-T1AS transformed phenotype. To determine whether G2B-10A cells enhance the tumorigenic growth of co-injected R2-T1AS cells in vivo, we used the nude mouse xenograft assay. Co-injecting R2-T1AS cells with G2B-10A cells ± PFA-fixation, revealed that G2B-10A cells promoted a ~3-fold increase in tumor growth, irrespective of PFA pre-treatment. These results indicate that soluble factors secreted by G2B-10A cells play a less important role in promoting R2-T1AS tumorigenesis in vivo, and that additional components are operative in the nude mouse xenograft assay. Finally, using array analysis, we found that both live and PFA-fixed G2B-10A cells induced R2-T1AS cells to secrete specific cytokines (IL-6 and GM-CSF), suggesting that cell-cell contact activates R2-T1AS cells.

Conclusions

Taken together, these data shift our understanding of adjacent benign epithelial cells in the cancer process, from passive, noncontributory cells to an active and tumor-promoting vicinal cell population that may have significant effects early, when benign cells outnumber malignant cells.

Reciprocal changes in gene expression profiles of cocultured breast epithelial cells and primary fibroblasts

The importance of epithelial-stroma interaction in normal breast development and tumor progression has been recognized. To identify genes that were regulated by these reciprocal interactions, we cocultured a nonmalignant (MCF10A) and a breast cancer derived (MDA-MB231) basal cell lines, with fibroblasts isolated from breast benign-disease adjacent tissues (NAF) or with carcinoma-associated fibroblasts (CAF), in a transwell system. Gene expression profiles of each coculture pair were compared with the correspondent monocultures, using a customized microarray. Contrariwise to large alterations in epithelial cells genomic profiles, fibroblasts were less affected. In MDA-MB231 highly represented genes downregulated by CAF derived factors coded for proteins important for the specificity of vectorial transport between ER and golgi, possibly affecting cell polarity whereas the response of MCF10A comprised an induction of genes coding for stress responsive proteins, representing a prosurvival effect. While NAF downregulated genes encoding proteins associated to glycolipid and fatty acid biosynthesis in MDA-MB231, potentially affecting membrane biogenesis, in MCF10A, genes critical for growth control and adhesion were altered. NAFs responded to coculture with MDA-MB231 by a decrease in the expression of genes induced by TGFbeta1 and associated to motility. However, there was little change in NAFs gene expression profile influenced by MCF10A. CAFs responded to the presence of both epithelial cells inducing genes implicated in cell proliferation. Our data indicate that interactions between breast fibroblasts and basal epithelial cells resulted in alterations in the genomic profiles of both cell types which may help to clarify some aspects of this heterotypic signaling.

Tumor-stromal interactions with direct cell contacts enhance proliferation of human pancreatic carcinoma cells

Pancreatic ductal adenocarcinoma is often characterized by an abundant desmoplastic stroma that is partially induced by activated pancreatic stellate cells (PSCs). Indirect co-culture has often been used to investigate the effects of cancer-stromal interactions on the proliferation of cancer cells, but the effects of cell-cell adhesion and juxtacrine signaling between cancer and stromal cells cannot be evaluated using this method. This study aimed to establish a simplified direct co-culture system that could be used to quantify populations of cancer cells in co-culture with PSCs, and to evaluate the effects of direct cell contact on the proliferation of cancer cells. We established three green fluorescent protein (GFP)-expressing pancreatic cancer cell lines and were able to quantify them with high reliability and reproducibility, even when co-cultured directly with PSCs, using a color plate reader. We assessed the differential effects of direct and indirect co-culture with PSCs on the proliferation of cancer cells, and found that the proliferation of GFP-expressing pancreatic cancer cell lines was dramatically enhanced by direct co-culture with PSCs, compared with the indirect co-culture system. We also found that direct co-culture of cancer cells and PSCs activated the Notch signaling pathway in both cell types. Direct cell contact between cancer cells and PSCs plays an important role in the control of cancer cell proliferation, and is essential to the understanding of tumor-stromal interactions.

Transformed epithelial cells and fibroblasts/myofibroblasts interaction in breast tumor: a mathematical model and experiments

It is well known that tumor and its microenvironment, or stroma, interact with each other and that this interaction plays a critical role in tumor initiation, growth, and metastasis. This interaction consists of complex relations between tumor cells, stromal cells such as fibroblasts, epithelial cells and immunocytes, the vascular system, the extracellular matrix, and cytokines secreted by the cells. Understanding these relationships may lead to new therapeutic approaches to cancer. In the present paper, we consider tumor-stroma crosstalk in a simple in vitro situation which involves interaction between tumor epithelial cells from breast cancer and a microenvironment consisting of just fibroblasts. The two populations of cells are separated by a semi-permeable membrane that allows only cytokines to cross over. We develop a mathematical model that includes two critical growth factors: TGF-beta, produced by the tumor cells, and EGF, secreted by the fibroblasts. The TGF-beta modifies the microenvironment by transforming fibroblasts into myofibroblasts. Myofibroblasts secrete higher concentrations of EGF than fibroblasts, thereby, increasing the proliferation of tumor cells. Thus already in this simple setup one sees a mutual interaction between tumor cells and their microenvironment. We conducted experiments which show good agreement with the model's simulations, hence confirming the model's ability to predict aspects of tumor cell behavior in response to signaling from fibroblasts.

Blockage of transdifferentiation from fibroblast to myofibroblast in experimental ovarian cancer models

Background

Tumour stromal myofibroblasts can promote tumour invasion. As these cells are genetically more stable than cancer cells, there has been enormous interest in developing targeted molecular therapies against them. Chloride intracellular channel 4 (CLIC4) and reactive oxygen species (ROS) have been linked with promoting stromal cell transdifferentiation in various cancers, but little is known of their roles in ovarian cancer. In this study, we examined the functional roles that both CLIC4 and ROS play in the process of ovarian cancer cell-stimulated or TGF-β1 induced fibroblast-to-myofibroblast transdifferentiation. We also examine whether it is possible to reverse such a process, with the aim of developing novel therapies against ovarian cancer by targeting activated transdifferentiated myofibroblasts.

Results

We demonstrate that TGF-β1 induced or CM^SKOV3 activate transdifferentiated myofibroblasts (fibroblasts). These fibroblasts mimic "reactive" stromal myofibroblasts and demonstrate significant up-regulation of CLIC4 expression and increased level of ROS production. Blocking the production of ROS with an antioxidant consequently reduces the expression of CLIC4, and is accompanied by disappearance of α-smooth-muscle actin (α-SMA), a myofibroblast marker, suggesting ROS acts as a signalling molecule that promotes and enhances CLIC4 activities in the myofibroblast transdifferentiaton process. Down-regulation of CLIC4 with a generic agent or specific siRNA both significantly reduces the expression of factors related to the phenotypes and functions of myofibroblasts, such as α-SMA, hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF), thus reversing the myofibroblast phenotype back to fibroblasts. These results convincingly show that ROS and CLIC4 are responsible for TGF-β1 induced fibroblast-to-myofibroblast transdifferentiaton and down-regulation of both is sufficient to block transdifferentiated myofibroblasts.

Conclusion

Molecular targeting of ROS and CLIC4 has the potential to develop novel therapies for ovarian cancer.

Breast cancer by proxy: can the microenvironment be both the cause and consequence?

Breast cancer is one of the most clear-cut examples of a solid tumor in which systemic cues play a decisive part in its development. The breast tissue is constantly subjected to changes in hormone levels and modifications in the microenvironment. This scenario is even more striking during tumor development because of the dramatic loss or aberration of basement membrane (BM) and myoepithelial cells and the gain of peritumoral myofibroblasts. We suggest that the microenvironment, defined here as all components of the mammary gland other than luminal and/or tumor epithelial cells, might be instrumental in maintaining organ integrity and in promoting, and at times even initiating, breast cancer development. As such, the tumor microenvironment and its constituents, alone or in combination, might serve as promising targets for therapy.

Improving decision-making in early breast cancer: who to treat and how?

Recent advances in primary and adjuvant treatment for early-stage breast cancer have reduced mortality rates, and improved the overall prognosis. Many patients can be cured, while others may survive for 10 years or more beyond diagnosis, thanks to a combination of preoperative therapy, surgery, radiotherapy, and systemic adjuvant therapy. Minimally invasive procedures, more effective drugs, and improved treatment regimens are helping to reduce breast cancer recurrences and deaths, while minimizing side effects and maintaining quality of life. Despite such improvements, a significant number of patients with early disease will relapse, including those who are clinically disease-free after primary and adjuvant therapy. Advances in breast tumor biology have led to the discovery of many different tumor types, and a uniform approach to treatment is no longer appropriate. Potential markers have been identified for the risk of relapse and responsiveness to a given therapy, thus treatment decisions and clinical guidelines, previously based on data from large patient populations, are changing to reflect a movement towards individually tailored treatment. Refinements in clinical practice will help physicians to identify the patients who will benefit the most from a particular approach, reducing overtreatment, and sparing patients unnecessary therapy. Genetic studies are helping to increase our understanding of the metastatic potential of tumors, leading to the development of adjuvant therapies for the prevention of metastases in selected patients. This article reviews the latest advances in treatment for early breast cancer, and explores how research and clinical practice are evolving to improve therapies and treatment decision-making, allowing physicians to optimize patient care.

Paradoxical antiproliferative effect by a murine mammary tumor-derived epithelial cell line

BACKGROUND

Despite significant advancement in breast cancer therapy, there is a great need for a better understanding of the mechanisms involved in breast carcinogenesis and progression, as well as of the role of epigenetic contributions from stromal cells in mammary tumorigenesis. In this study, we isolated and characterized murine mammary tumor-derived epithelial and myofibroblast cell lines, and investigated the in vitro and in vivo effect of cellular soluble factors produced by the epithelial cell line on tumor cells.

METHODS

Morphology, immunophenotype, cytogenetics, invasiveness, and tumorigenicity of epithelial (LM-234ep) and myofibroblast (LM-234mf) cell lines isolated from two murine mammary adenocarcinomas with common ancestor were studied. The in vitro effects of LM-234ep conditioned medium on proliferation, cell cycle distribution, and expression of cell cycle proteins, were investigated in LM-234mf cells, mouse melanoma cells (B16-F10), and human cervical adenocarcinoma cells (HeLa). The in vivo anti-tumor activity of LM-234ep conditioned media was evaluated in subcutaneous tumors formed in nude mice by B16-F10 and HeLa cells.

RESULTS

LM-234ep cells were found to be cytokeratin positive and hipertriploid, whereas LM-234mf cells were alpha-smooth muscle actin positive and hypohexaploid. Chromosome aberrations were found in both cases. Only LM-234mf revealed to be invasive in vitro and to secrete active MMP-2, though neither of the cell types were able to produce progressing tumors. LM-234ep-derived factors were able to inhibit the in vitro growth of LM-234mf, B16-F10, and HeLa cells, inducing cell cycle arrest in G0/G1 phase. The administration of LM-234ep conditioned medium inhibited the growth of B16-F10 and HeLa tumors in nude mice.

CONCLUSION

Our data suggest the existence of epithelial cell variants with tumor suppressive properties within mammary tumors. To our knowledge, this is the first report showing antiproliferative and antineoplastic activities induced by tumor-derived epithelial cells.

Secretion of Cytokines in Breast Cancer Cells: The Molecular Mechanism of Procathepsin D Proliferative Effects

Procathepsin D (pCD) is a major secreted protein in estrogen receptor-positive (ER+) breast cancer cell lines. Several independent studies have documented pronounced mitogenic effect of secreted pCD on cancer tissue-derived cell lines, including those from breast, lung, and prostate cancer. It has also been shown that the proliferative effect of pCD involves both autocrine and paracrine modes of action. Recent studies have suggested that pCD could act as a key paracrine communicator between cancer and stromal cells. We have shown earlier that the proliferative activity of pCD depends on the activation peptide sequence of pCD. The present study casts light on the mechanism by which pCD influences the proliferation of cancer cells expressing the ER. Results described in the current paper clearly show that pCD initiates secretion of cytokines interleukin-4 (IL-4), IL-8, IL-10, IL-13, macrophage inflammatory protein-1beta and (MIP-1beta) from such tumor cells. Secreted cytokines take part in the proliferation of the cancer cells, as proven by selective inhibition using antibodies. In addition, expression of cytokine receptors on tested cell lines corresponded to the effects of individual cytokines. An analogous pattern was also observed for fibroblasts, which, under physiologic conditions, are the cells in closest contact with the tumor tissue and play a role in tumor growth and invasion. Our observations were further supported by coculture experiments that are in agreement. Although very similar in response to addition of pCD, the invasive ER- cells do not secrete cytokines. Together with previous in vivo results, these data point to pCD as one of key molecules for therapeutic attack in breast cancer.

Reciprocal Modifications of CLIC4 in Tumor Epithelium and Stroma Mark Malignant Progression of Multiple Human Cancers

PURPOSE

CLIC4, a member of a family of intracellular chloride channels, is regulated by p53, c-Myc, and tumor necrosis factor-alpha. Regulation by factors involved in cancer pathogenesis, together with the previously shown proapoptotic activity of CLIC4, suggests that the protein may have a tumor suppressor function. To address this possibility, we characterized the expression profile, subcellular localization, and gene integrity of CLIC4 in human cancers and determined the functional consequences of CLIC4 expression in tumor epithelium and stromal cells.

EXPERIMENTAL DESIGN

CLIC4 expression profiles were analyzed by genomics, proteomics, bioinformatics, and tissue microarrays. CLIC4 expression, as a consequence of crosstalk between stroma and epithelium, was tested in vitro by coculture of breast epithelial tumor cells and normal fibroblasts, and the functional consequences of CLIC4 expression was tested in vivo in xenografts of human breast tumor cell lines reconstituted with CLIC4 or mixed with fibroblasts that overexpress CLIC4 transgenically.

RESULTS

In cDNA arrays of matched human normal and tumor tissues, CLIC4 expression was reduced in renal, ovarian, and breast cancers. However, CLIC4 protein levels were variable in tumor lysate arrays. Transcript sequences of CLIC4 from the human expressed sequence tag database and manual sequencing of cDNA from 60 human cancer cell lines (NCI60) failed to reveal deletion or mutations in the CLIC4 gene. On matched tissue arrays, CLIC4 was predominantly nuclear in normal human epithelial tissues but not cancers. With advancing malignant progression, CLIC4 staining became undetectable in tumor cells, but expression increased in stromal cells coincident with up-regulation of alpha-smooth muscle actin, suggesting that CLIC4 is up-regulated in myofibroblasts. Coculture of cancer cells and fibroblasts induced the expression of both CLIC4 and alpha-smooth muscle actin in fibroblasts adjacent to tumor nests. Introduction of CLIC4 or nuclear targeted CLIC4 via adenovirus into human breast cancer xenografts inhibited tumor growth, whereas overexpression of CLIC4 in stromal cells of xenografts enhanced tumor growth.

CONCLUSION

Loss of CLIC4 in tumor cells and gain in tumor stroma is common to many human cancers and marks malignant progression. Up-regulation of CLIC4 in tumor stroma is coincident with myofibroblast conversion, generally a poor prognostic indicator. Reactivation and restoration of CLIC4 in tumor cells or the converse in tumor stromal cells could provide a novel approach to inhibit tumor growth.

Identification of squamous cell carcinoma associated proteins by proteomics and loss of beta tropomyosin expression in esophageal cancer

AIM: To assess the proteome of normal versus tumor tissue in squamous cell carcinoma of the esophagus (SCCE) in Iranian patients and compare our results with former reports by using proteomics.

METHODS: Protein was extracted from normal and tumor tissues. Two dimensional electrophoresis was carried out and spots with differential expression were identified with mass spectrometry. RNA extraction and RT-PCR along with immunodetection were performed.

RESULTS: Fourteen proteins were found whose expression levels differed in tumor compared to normal tissues. Mass spectrometric analysis resulted in the identification of β-tropomyosin (TMβ), myosin light chain 2 (and its isoform), myosin regulatory light chain 2, peroxyredoxin 2, annexinIand an unknown polypeptide as the down regulated polypeptides in tumor tissue. Heat shock protein 70 (HSP70), TPM4-ALK fusion oncoprotein 2, myosin light polypeptide 6, keratinI, GH16431p and calreticulin were the up-regulated polypeptides found in tumor tissue. Several of these proteins, such as TMβ, HSP70, annexinI, calreticulin, TPM4-ALK and isoforms of myosins, have been well recognized in tumorigenesis of esophageal or other types of cancers.

CONCLUSION: Our study not only supports the involve-ment of some of the formerly reported proteins in SCCE but also introduces additional proteins found to be lost in SCCE, including TMβ.

Degranulating mast cells in fibrotic regions of human tumors and evidence that mast cell heparin interferes with the growth of tumor cells through a mechanism involving fibroblasts

BACKGROUND

The purpose of this study was to test the hypothesis that mast cells that are present in fibrotic regions of cancer can suppress the growth of tumor cells through an indirect mechanism involving peri-tumoral fibroblasts.

METHODS

We first immunostained a wide variety of human cancers for the presence of degranulated mast cells. In a subsequent series of controlled in vitro experiments, we then co-cultured UACC-812 human breast cancer cells with normal fibroblasts in the presence or absence of different combinations and doses of mast cell tryptase, mast cell heparin, a lysate of the human mast cell line HMC-1, and fibroblast growth factor-7 (FGF-7), a powerful, heparin-binding growth factor for breast epithelial cells.

RESULTS

Degranulating mast cells were localized predominantly in the fibrous tissue of every case of breast cancer, head and neck cancer, lung cancer, ovarian cancer, non-Hodgkin's lymphoma, and Hodgkin's disease that we examined. Mast cell tryptase and HMC-1 lysate had no significant effect on the clonogenic growth of cancer cells co-cultured with fibroblasts. By contrast, mast cell heparin at multiple doses significantly reduced the size and number of colonies of tumor cells co-cultured with fibroblasts, especially in the presence of FGF-7. Neither heparin nor FGF-7, individually or in combination, produced any significant effect on the clonogenic growth of breast cancer cells cultured without fibroblasts.

CONCLUSION

Degranulating mast cells are restricted to peri-tumoral fibrous tissue, and mast cell heparin is a powerful inhibitor of clonogenic growth of tumor cells co-cultured with fibroblasts. These results may help to explain the well-known ability of heparin to inhibit the growth of primary and metastatic tumors.